This is from liberty but before I copy it in, you do realise that not only a degree a clinical psychologist makes?
A caution is not a criminal conviction, so if you are asked whether you have any previous convictions you may say no. However, the police will retain records of your caution in the Police National Computer. This record will normally be stepped down after 5 years but will never be deleted.
If you apply for jobs, professions or occupations that require you to disclose your criminal record, such as teacher, nurse, solicitor or prison officer (see here for a full list of exempted occupations), this will show not just details of convictions, but also of cautions, warnings or reprimands.
However, this does not necessarily mean that you would be refused a job on the basis of the caution. It would not mean that you were unfit for a particular job. The organisations which are entitled to make applications to the CRB for criminal record checks are also obliged to adhere to a Code of Practice to ensure that information released by the CRB is used sensibly and fairly.
If you think that your prospective employer might take into account your caution and think it is irrelevant to the job applied for, you can write to them explaining the circumstances of the caution and why you consider it irrelevant. If you are denied employment on the basis of the caution, you may be able to challenge the decision and should seek legal advice.